In the conventional art, an identifying method for a value bill is usually carried out by collecting image features through a contact image sensor. In the field of image-based pattern identification, it is necessary to collect to-be-identified images by using a sensor. If image resolution is insufficient, the correctness of the identifying result will be greatly reduced, especially between to-be-identified objects which are easy to be confused, such as “O” and “D” in character identification. Although the computer technology changes rapidly, a very high-end hardware platform will not be chosen in considerations of cost, the hardware platform is chosen only to satisfy actual demand. In this case, in practice, due to differences between hardware and the diversity of identification space, more objects which are easy to be confused will be identified wrongly. Thus, an identifying method based on color data is developed to identify a type of a value bill.
The color data refers to a set of values of three colors of R, G and B which is collected by a color sensor. It is an intuitive and fast method to identify a value bill based on color data of the value bill. A process for identifying color data includes two parts, which are feature extraction and identification, and the robustness of the extracted feature directly affects the accuracy of identification. The extraction of color features mainly has the following problems. On one hand, since the color data is a result of a common effect of color in a certain region of a value bill, when the surface of a signal acquisition area is non-solid-colored, the color data will have a greater deviation from the true color. On the other hand, for a same color acquisition area, different textures have different reflected intensities, which cause the color sensor to receive signals of different intensities, resulting in instability of the color data.
For the above reasons, features obtained from the feature extraction are difficult to be robust, resulting in the inability to accurately identify the type of the value bill.